El British English It is a dialect of the English language and has a series of features that differentiate it especially from American English. Within the UK, there are different regional variants of British English, including Cockney. You have all the information in: «What is the language of the UK? What accents and dialects does it have?«.
You have all the information in: "What is the language of the UK? What accents and dialects does it have?".